High speed chopper



March 7, 1961 H. l. CHAMBERS ET AL HIGH SPEED CHOPPER Filed May 26, 1958INVENTOR. HERBERT I CHAMBERJ ALBERT M FISCHER BY United States PatentHIGH SPEED CHOPPER Herbert I. Chambers and Albert W. Fischer, Pasadena,

Calif., assignors, by mesne assignments, to Consolidated ElectrodynamicsCorporation, Pasadena, Cali, a corporation of California Filed May 26,1958, Ser. No. 737,923

8 Claims. (Cl. 200--90) This invention relates to electromechanicaldevices for making and breaking electrical'circuits, and moreparticularly, is concerned with a high speed device for making andbreaking circuits which can be used as a relay or as a high speedchopper.

Magnetically operated switches take a variety of forms, such as relaysfor switching large currents in response to control signals of muchsmaller levels. Also, magnetically operated mechanical switches are usedfor chopping D.C. signals at the rate of an AC. signal applied to theelectromagnetic circuit. The relay-type of device may also be used forcommutating or switching in a scanning manner for discrete periods oftime. Whatever form the electromechanical switching device takes, itsfrequency of operation is limited by the relatively large mechanicalmass required to provide suitable magnetic properties, and, in addition,is limited by the large equivalent electrical mass in the form ofinductance of the electromagnetic circuit. By very careful design, boththe mechanical and electrical mass of such relay devices have beenreduced to improve performance, but reliable operation of such devicesat frequencies as high as 1,000 cycles per second, for example, is notgenerally attainable.

The present invention is directed to an electromechanical switchingdevice which may be used as a simple relay, or a chopper, and capable ofopera-ting reliably at frequencies of several thousand cycles and evenhigher. This is accomplished by reducing the mechanical mass to that ofa single fine conductive wire, and by reducing the electrical equivalentmass by using a permanent magnetic field.

In brief, the relay apparatus of the present invention includespermanent magnet means defining an elongated magnetic flux gap. Aflexible current-wnductive element is supported in the gap, thesupporting means including at least one resilient support at one end ofthe conductive element. Means is provided for passing a current throughthe conductive element for deflecting the conductive element laterallydue to the interaction of the current in the magnetic field in the gap.The resilient support permits the element to deflect laterally byallowing the ends of the element to move closer together. Contact meansis provided which is actuated by the lateral movement the element inresponse to the current applied therethrough.

For a more complete understanding of the invention, reference should behad to the accompanying drawing, wherein:

Fig. 1 is an elevational view partly cut away, showing acircuit-breaking device according to one form of the present invention;

Fig. 2 is an end view' of the form of the invention shown in Fig. 1;

substantially on the line 4-4 of Fig. 3; and Y NSC Fig. 5 is a sectionalview taken substantially on the line 5--5 of Fig. 3.

Referring to the form of the invention as shown in Figs. 1 and 2, thenumeral 10 indicates generally a frame which is substantiallychannel-shaped, with the righthand upright member 12 extendingconsiderably higher than the lefthand upright member 14. Mounted to theframe member it) is a magnet block 16, which may be of Alnico magnetmaterial. The block is secured to the frame member 10 by means of screws18. The magnet block 16 extends between the two upright end portions 12and 14 of the frame member 10.

A pair of pole pieces 20 and 22 are bolted on either side of themagnetic block 16, as by means of bolts 24 extending through the block16. The pole pieces 20 and 22 project upwardly and extend the fulllength of the block 16 between the end portions 12 and 14 of the frame10. The upper end of the pole pieces 21) and 22 respectively haveinwardly projecting portions 26 and 27 which are tapered along theirinner opposed edges to define an elongated magnetic gap 28. It will beapparent that the gap extends the full length of the pole pieces 20 and22.

A fine conductive wire element 30 is secured at one end to the uprightportion 12 of the frame member 10. The wire element is supported at theother end by a cantilever spring 32 which is curved at its upper end asindicated at 34. The fine wire element is drawn across the curved upperend and anchored as by means of solder or other suitable means at itsend 36. The cantilever spring 32 extends downwardly to a point oppositethe lower end of the frame 10 and is rigidly secured at the lower end bymeans of a screw 38 which clamps the cantilever spring 32 together witha set of contact elements, to be hereinafter described, between aplurality of insulating washers to the frame 10. Thus the cantileverspring 32 applies tension to the wire element 30, and at the same timesupports it in position in the magnetic gap 28 formed byv tion at thecontacts if so desired. A plurality of insulat-v ing washers, asindicated at 54, clamp the cantilever spring elements 32, 50, and 52 inconventional manner of multi-contact relays. Conductive leads 56 and 5'3are provided for bringing out electrical connections to the contacts 40and 42 respectively.

In operation, a potential is applied between the ends of the fine wireelement 30, as by connecting a potential source between the lower end ofthe cantilever spring 32 and the frame In. The resulting current passingthrough the Wire element 30 interacts with the magnetic field in the gap28 to produce a lateral displacement of the wire element 30. Thislateral displacement is in a ventical plane in the arrangement shown inFigs. 1 and 2.

Lateral displacement of the wire element 30 causes the ends thereof tomove closer together. As a result, the cantilever spring support element32 is caused to move'to the right so as to close the contacts 42 and 48and to open v the input causing contacts to open and contacts to closeAn alternating signal can be applied across the input if desired,causing the spring element 30 to vibrate at the frequency of the inputsignal. As a result, the contacts are caused to make and break at twicethe, frequency of the input signal, resulting in a high frequencycliop'per.

An alternative embodiment of the present invention is shown in Figs. 3,4 and 5. in this arrangement, the frame of the device consists of anupper plate 60 and a lower plate 62, a pair of cylindrical members 54and 6:5, and a central plate 63. The central plate is clamped betweenthe two cylindrical members 64 and es, and end plates 6b and 62 areclamped to the outer edges of the cylindrical members 64 and 66 by boltmembers, such as indicated at '70, which are secured to the lower plate62 and have nuts 72 which clamp against the upper end plate 60. Annularinsulating spacers 7d and 7d are preferably provided between the upperand lower plates 6d and 62 and the cylindrical members 64 and ed toinsulate the plates electrically.

A conductive Wire element 73 is anchored at either end respectively inthe upper and lower plates so and 62. The wire element '78 is formedwith crimped sections 30 to provide flexible tensioning of the Wireelement 7%, or may have a tension spring similar to 32.

As best seen in Fig. 4, the central plate 62; is provided with a centralopening 82 through which the wire element 73 passes. The central plate68 is cut to form a pair of integral cantilever supported adjustablearms 84 and 86. Suitable screw means, such as indicated at may beprovided for bending the arms toward each other to provide an adjustmentof the spacing between the outer ends of the cantilever arms 84 and 86.

The wire element 78 is immersed in a magnetic field formed by a pair ofpole pieces positioned above and below the central plate 68, the polepieces being indicated at 90 and 92. The pole faces are secured toblocks of magnetic material such as Alnico, as indicated at 94 and 96,the blocks having curved surfaces to fit against the inner surfaces ofthe cylindrical members 6 and 66. With the wire element immersed in amagnetic field, current passing through the magnetic element will causeit to deflect. The current may be connected by suitable leads connectedto the end plates 60 and 62. These end plates are insulated from eachother by virtue of the annular insulating rings 74 and 76 and byinsulating bushings 98 through which the connecting bolts 70 pass.

Lateral movement of the wire element '78 in response to current passedtherethrough is utilized to maize and break contacts, the contacts beingbest shown in Fig. 4. One set of contacts comprises a spring wire 100which is anchored in a hole 102 in the central plate by a suitableinsulating cement. The wire 100 projects into the opening 82 in thecentral plate and is positioned to one side of the wire element 78. Thewire contact element 100 is normally in contact with an associated stoplil' i which is secured in an opening 106 in the adjustable cantileverarm 34 by suitable insulating cement.

Similarly, a wire contact element 103 is secured in a hole 110 in thecentral plate and projects into the opening 82 to the opposite side ofthe wire element 73 from the contact element 100. An associated stopelement 112 is secured in an opening 114 in the cantilever arm 86.

The wire element 78 is provided with a small insulated contact 116 witha ribbon pigtail 117, the contact 116 engaging the wire contact elements100 and 103. The pigtail 117 extends to an insulated support pin 119 formaking an external electrical connection. ner, lateral displacement ofthe wire element 7% in two directions respectively closes the contactstilt) and 163 with contact 116. Screws 88 adjust the position of thestops 104 and 112 to vary the spacing between the contacts 100 and 108.Electrical connections are made to the pigtail 117 and the contactelements 100 and 108.

Sponge rubber damping pads 118 are preferably provided, which are.cemented. into position and fillthe space In this manbetween the contactelements and 108 and the sides of the opening 82. These pads preventbouncing or vibration of the contact elements 160 and 108.

The entire assembly is mounted inside a protective housing which is intwo parts including an upper cupshape cover 120 and a base member 122.The base member and cover member are telescopically joined and brazedtogether at the joint to provide a hermetically sealed container.Electrical connecting pins 124 are provided in the base member 122,which extend through glass seals 126 for providing electricalconnections to the element 78 and the contacts 100, 103, and 116. Thewire connections have not been shown for the sake of clarity.

From the above description it will be seen that an electromechanicalcircuit breaking device has been provided which is capable of operatingat high speeds. The device can be used as a relay or as a chopper. Themechanical inertia of the device is very small so that the moving massas represented by the wire element is extremely small. The electricalequivalent inertia is very small because the inductance of the singlewire conductor is of course extremely small. Because of the smallinductive fields, the noise level is very low so that the deviceprovides excellent switching performance.

What is claimed is:

1. A high speed switching device comprising a flexiblecurrent-conductive straight wire element, magnetic means defining anelongated magnetic gap, means for supporting the conductive element inthe gap inciuding a resilient support at one end of the element formaintaining tension on the Wire element, the elongated magnetic gapextending substantially the full length of. the flexible element, meansfor passing a current through the flexible element, the currentproducing a lateral deflection of the flexible element due to theinteraction of the current and the magnetic field in the gap, theresilient; support permitting the element to deflect laterally byallowing the ends of the element to move closer together, and contactmeans actuated by movement of the element in response to the currentapplied through the element, the contact means being electricallyinsulated from the flexible element to provide switching of an isolatedcircuit.

2. Apparatus as defined in claim 1 wherein said resilient supportincludes a cantilever spring to which the element is secured at one end,and the contact means includes contacts insulatedly supported by thecantilever spring and movable therewith and fixedly supported contactspositioned adjacent the moving contacts, whereby the contacts arebrought in and out of engagement by movement of the flexible element inresponse to variations in the current passed therethrough.

3. Apparatus as defined in claim 2 further including a source ofalternating current electrically connected across the flexible elementfor imparting a periodic movement to the flexible element and associatedcantilever spring, whereby the contacts are periodically engaged toefiect a chopper operation.

4. A high speed switching device comprising a flexiblecurrent-conductive wire element, magnetic means doth ing an elongatedmagnetic gap, means for supporting the conductive element in the gapunder tension, the eiou-- gated magnetic gap extending substantially thefuli length of the flexible element, means for passing a current throughthe conductive element, the current producing a lateral deflection ofthe center of the conductive wire element due to the interaction of thecurrent and the magnetic field in the gap, and contact means actuated bylateral movement of the wire element in response to the current appliedthrough the element, the contact means being electrically insulated fromthe flexible element to provide switching of an isolated circuit.

5. Switching apparatus comprising a main frame including a pair ofspaced plates, a wire element extending between said plates andresiliently supported therefrom,

a pair of contact elements positioned respectively on either side of thewire element, a contact sleeve insulatedly mounted on the wire elementand adapted to engage the contact elements when the center region of theWire element is laterally displaced, means for resiliently supportingthe contact elements from the main frame, a pair of adjustable stopsnormally engaging respectively each of the first pair of contacts foradjusting the spacing of the contacts, and magnetic means mounted on themain frame including pole pieces positioned on either side of the wireelement for immersing the wire element in a magnetic field.

6. Switching apparatus comprising a main frame, a

wire element resiliently supported by the frame, a pair of contactelements positioned respectively on either side of the wire element, asleeve contact on the wire element adapted to engage the contactelements when the center region of the wire element is laterallydisplaced, means for resiliently supporting the contact elements fromthe main frame, a pair of stops normally engaging respectively each ofthe first pair of contacts, and magnetic means mounted on the main frameincluding pole pieces positioned on either side of the wire element forimmersing the wire element in a magnetic field.

7. Switching apparatus comprising a main frame, a wire elementresiliently supported by the frame, a pair of contact elementspositioned respectively on either side of the wire element, means forresiliently supporting the contact elements from the main frame, wherebythe contact elements' are respectively movable with lateral movement inopposite directions of the wire element, a contact insulatedly securedto the wire element and movable 6 therewith, displacement of thelast-named contact by the wire element moving the contact into and outof engagement with the first pair of contacts, and magnetic meansmounted on the main frame including pole pieces positioned on eitherside of the wire element for immersing the wire element in a magneticfield.

8. Switching apparatus comprising a main frame, a wire elementresiliently supported under tension by the frame, a pair of contactelements positioned respectively on either side of the wire element,means for resiliently supporting the contact elements from the mainframe, a contact member secured to the wire element and engaging thecontact elements, whereby the contact elements are respectively movablewith lateral movement in opposite directions of the wire element,magnetic means providing a unidirectional magnetic field mounted on themain frame including pole pieces positioned on either side of the wireelement for immersing the Wire element in a constant magnetic field, andmeans for passing an alternating current through the wire element tocause the wire element to oscillate in the magnetic field.

References Cited in the file of this patent UNITED STATES PATENTS CookFeb. 14,

